1. Field of the Invention
The present invention relates to an applicator and an application method. Specifically, the present invention relates to an applicator which applies a coating liquid onto an upper surface of a continuously traveling web, and an application method using the applicator.
2. Description of the Related Art
Hitherto, in a case where a functional layer such as an easy adhesion layer or an antistatic layer is formed on the surface of a web, a coating liquid is applied onto the surface of the web to form a coating film. As a method of applying the coating liquid to the web surface, a number of application methods including a roll application method, a die application method, a spray application method, a bar application method, and the like are known. Among the methods, the bar application method has been widely used in a case of thinly and evenly applying a low-viscosity coating liquid.
In the case where the coating liquid is applied by the bar application method, a bar, a barrier plate, and the like are provided on the lower surface side of a continuously traveling web, and the coating liquid is applied onto the lower surface of the web while the coating liquid overflows. In the case of applying the coating liquid onto the lower surface of the web, various measures are considered to allow the coating liquid to have an even and desired film thickness.
However, in the case of applying the coating liquid onto the lower surface of the web, in order to prevent the generation of coating unevenness, the coating liquid needs to overflow. Therefore, a complex mechanism for circulating the overflowing coating liquid is necessary. In addition, in the case of coating the lower surface, since the coating liquid is circulated, foreign matter such as lumps in the coating liquid is likely to be generated, and there is a problem of the incorporation thereof into the coating liquid. In the case where foreign matter is incorporated into the coating liquid, the foreign matter may infiltrate into the coating surface, and thus there is a risk of damage to the evenness of the coating surface.
In order to solve the problems regarding the coating of the lower surface, a method of applying a coating liquid onto the upper surface side of a web by the bar application method has been examined. For example, JP2009-202132A and JP1993-177159A (JP-H05-177159A) disclose a method of applying a coating liquid onto the upper surface of a web using a bar coater. In JP2009-202132A, an applicator which has a bar and a barrier plate on the upper surface of a web and has various support rolls is disclosed. In addition, in JP1993-177159A (JP-H05-177159A), an applicator having a bar and a barrier plate (guide plate) on the upper surface of a web is disclosed. In the documents, the coating liquid is applied by forming a liquid mass of the coating liquid on the upper surface of the web.
JP2009-240995A is an example of the related art.